sxiv is an alternative to feh and qiv. Its only dependencies besides
xlib are imlib2 and giflib. The primary goal for writing sxiv is to
create an image viewer, which only has the most basic features required
for fast image viewing (the ones I want). It has vi key bindings and
works nicely with tiling window managers. Its code base should be kept
small and clean to make it easy for you to dig into it and customize it
for your needs.
